Flying out early with a pile of luggage is rough. If you booked four checked bags, you’re hoping you can drop two, go back to the hotel, then return with the other two. Totally makes sense when it’s a short train ride and you’re traveling alone.
The catch is most airlines want you to check everything in one go because once your bags are tagged, you’re supposed to stay in the airport. Some agents will let you do a second drop if the counter is still open, but it really depends on the airport and the airline. I’ve seen it work and I’ve seen people get turned away.
If it were me, I’d call the airline just to see if that airport allows a second bag drop. Otherwise the painless answer might be to just grab the taxi and avoid any drama at 4 in the morning.